US 7921905 B2
A plastic intercooler assembly includes a plurality of plastic tubes that extend between plastic end plates. The plastic tubes are secured to the end plates to provide the desired seal between the end plates and the ends of the tubes. The plastic tubes are attached utilizing plastic welding methods that reduce assembly time and cost.
1. A plastic intercooler assembly comprising:
a first end plate;
a second end plate; and
a plurality of plastic tubes that extend between the first plate and the second plate that are laser welded to each of the first end plate and the second end plate, wherein the plurality of plastic tubes comprise a first group fabricated from a first plastic material and a second group fabricated from a second plastic material that is different than the first plastic material.
2. The assembly as recited in
3. The assembly as recited in
This invention generally relates to an intercooler for use in a motor vehicle. More particularly, this invention relates to a plastic intercooler and method of fabricating and assembling a plastic intercooler.
An intercooler is a heat exchanger for transferring heat from one fluid into another fluid that is not physically in contact. One example application of an intercooler is for cooling turbo compressor exhaust gases prior to use in a turbocharger or as charge air. It is desired to cool the exhaust gases to reduce volume and increase the amount of charge air that can be input into the cylinder. The hot air is directed through a plurality of tubes over which cooling air flows. Heat from the hot air is transferred through the tubes and carried away by the cooler air.
A conventional intercooler includes a plurality of tubes that span between manifolds or tanks on each end. The tanks typically comprise an open internal volume in communication with an open end of the plurality of tubes. The tanks include an inlet to provide for a single inlet or outlet for air flow through the intercooler. The tubes are typically formed from metals such as aluminum, copper or brass that are welded or brazed to end plates. The end plates are in turn attached to the tanks to provide the desired inlet and outlet for the intercooler.
Disadvantageously, metal tube construction and fabrication provide a relatively heavy and cumbersome device. Further, the use of metal tubes limits the configuration of the intercooler. The constraints on devices installed within vehicles are becoming more demanding as related to cost, weight and flexibility of design.
Accordingly, it is desirable to design and develop improved methods and materials for fabricating and assembling an intercooler device.
A plastic intercooler assembly includes a plurality of plastic tubes that extend between plastic end plates. The plastic tubes are secured to the end plates to provide the desired seal between the end plates and the ends of the tubes.
The plastic tubes are attached utilizing plastic welding methods that reduce assembly time and cost. An example intercooler assembly includes an outer perimeter with the inlet and outlet disposed within the outer perimeter. The plurality of tubes includes tubes of differing lengths to accommodate the shape of the tanks and the inlet and outlet. The different length of tubes accommodates a curved profile of the first and second end plates that in turn provides for the efficient use of space within the outer perimeter of the intercooler assembly.
Another example intercooler assembly includes a first group of tubes that have a stable operation temperature that is lower than the operating temperature of a second group of tubes. As the first group of tubes and the second group of tubes operate at different temperatures, different materials are utilized to perform efficiently at the different temperatures thereby accommodating the thermal gradient across the intercooler assembly.
Another example intercooler includes a manifold from which generally U-shaped tubes extend that are attached to the manifold at both ends. The U-shaped tubes eliminate a significant amount of joints to simplify assembly and fabrication of the intercooler assembly.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
The incoming air 28 is at a high temperature and enters the inlet 26 that is in communication with the plurality of tubes 16. The high temperature air flows through the plurality of tubes 16 to the first tank 18. As the air flows through the plurality of tubes 16, a portion of the heat is rejected through the plurality of tubes 16 to a cooling stream 30 that flows across and around each of the plurality of tubes 16. The exhaust air 24 exiting the outlet 22 is therefore at a lower temperature than the air entering the inlet 26.
The intercooler assembly 10 includes an outer perimeter 32. Conventional intercoolers include inlet and outlet housings that extend from the outer perimeter 32. The example intercooler assembly 10 includes the inlet 26 and outlet 24 that are disposed within the outer perimeter 32. The plurality of tubes 16 includes tubes of differing lengths to accommodate the shape of the tanks 18, 20 and the inlet 26 and outlet 24. The plurality of tubes 16 include a first tube 35 including a first length 34 and a second tube 37 having a second length 36 that is greater than the first length. The different length of tubes accommodates the curved profile of the first and second end plates 12, 14. The curved profile of the end plates 12, 14 provide for the efficient use of space within the outer perimeter 32 of the intercooler assembly 10.
The cooling air stream 52 begins at a coolest temperature illustrated at arrow 54 prior to entering into the intercooler assembly 40. As the cooling air stream flows through the intercooler assembly 40 and accepts heat radiated from the plurality of tubes 42, it becomes warmer. Accordingly, the arrow 56 represents cooling airflow 52 at a temperature greater than the temperature of the cooling airflow prior to entering the intercooler assembly 40. Finally, the air exiting the intercooler is at a warmest temperature 58.
The plurality of tubes 42 are therefore exposed to different temperature cooling airflow that affect the thermal efficiency of cooling air within the intercooler. Further, the tubes 42 that receive the cooling airflow 52 first are cooled to a lowest temperature, with the temperature of each of the tubes gradually becoming warmer the further away from that first tube. The material that is utilized in fabricating the plastic tubes 42 is selected according to the thermal gradient experienced during operation. Further, the material for the plastic tubes 42 is selected to accommodate the stable temperature at which the plurality of tubes 42 will operate. In the example intercooler assembly 40 a first group of tubes 60 have a stable operation temperature that is lower than the operating temperature of as second group of tubes 62. As the first group of tubes 60 and the second group of tubes 62 operate at different temperatures, different materials will perform efficiently at the different temperatures.
Plastic material utilized for producing the plastic tubes 42 are provided at different grades that relate to material properties and operating temperatures. For example, plastic material that must operate in an environment of higher temperatures is different than material that operates at lower temperatures. As appreciated, in many instances, the material that is to operate at the higher temperatures is more expensive that the material that is to operate at lower temperatures. In the example intercooler assembly 40 the first group of tubes 60 is fabricated from a first material and the second group of tubes 62 are fabricated from a second material different than the first material. The first material is provided for operation at a lower temperature than the second material. This provides for the efficient use of materials that accounts for the thermal gradient across the intercooler assembly 40.
A portion of laser energy is transmitted through the laser transparent flange 68 and is absorbed by the laser absorbent end plate 72. Absorption of the laser energy by the end plate cause a localized melting of plastic material that in turn causes additional heating of the laser transparent flange 68. Melted material from both the end plate 72 and the flange 68 intermingle and cool, generating the desired weld and seal between the tube 66 and end plate 72. The laser 74 or the tube 66 and end plate 72 are rotated to provide a circumferential weld of the flange 66 to the end plate 72.
Further, the angled orientation of the laser device 74 relative to the axis 86 and the surface of the end plate 84 provide for directing and creating the joint between the tube and end plate as is desired.
As appreciated, an intercooler assembly can include hundreds of tubes that all require attachment and sealing to an endplate or some other end structure through which air is directed into the tubes. Therefore, processes for joining the plastic tubes to the end structures, endplates that reduce cycle time and cost are beneficial.
As appreciated, the tube is shown attached to an endplate in the illustrated examples. The tubes may also be attached to other end assemblies that provide for directing air for cooling through the intercooler.
In this example, the end plate 120 is fabricated from a laser transparent material and the tube 122 is fabricated from a laser absorbent material. Laser energy from each of the laser directing ends 114 generates a single weld bead. The fiber optic device 112 includes a sufficient number of laser directing ends 114 to completely encircle the desired joint. In the example case, the tube 122 is circular, and thereby the weld seam is configured circumferentially about the interface between the tube 122 and the end plate 120.
The washer 130 is fabricated from a plastic material that melts responsive to the energy 134 input from the induction heating device 132. The plastic material can be flexible, such as for example a thermoplastic vulcanizate material that is flexible to provide a sealing function. The induction heating device 132 is as known to produce heat in metal parts caused by the inductive energy 134 transmitted into the washers 130.
In process, an entire intercooler assembly with a plurality of tubes 126 is assembled with the corresponding washers 130. The fit of the tubes 126 in the openings 136 along with the washers 130 maintain the desired relative position of the tubes 126 to the end plate 128. The entire device is then exposed to the inductive energy 134. The inductive energy 134 does not substantially affect the plastic material, but does cause the desired localized melting to form the desired weld joints between the tubes 126 and the end plate 128.
The bends 158 provided in each of the plurality of tubes 156 accommodate for these differences in length by compressing to eliminate undesired gaps and fits. The bend 158 includes a length 166. The length 166 of the bend is variable and adjustable. During assembly, pressure is exerted on each end 152, 154 to the length 160. The pressure provides for the compression of some of the tubes 158 as facilitated by the bends 158. The compressions provide for a desired fit without tightly held tolerances that increase material and assembly costs.
As was discussed above, an intercooler can include hundreds of tubes that all require attachment and sealing to an end plate or manifold. The use of the friction welding method described in references to
The U-shaped tubes 194 eliminate a significant amount of joints to simplify assembly and fabrication of the intercooler assembly. As appreciated, each tube 194 eliminates at least two joints that would otherwise be required for conventionally configured intercooler assemblies.
In the example intercooler assembly 190, cool air or fluid is directed through the tube 194 that is exposed to a hot air stream 206. The hot air stream 206 rejects heat into the cool air within the tube 194. The now warm air returns to the manifold 192 to the warm portion 196 separated from the cool portions 198. A bracket 200 is provided to stabilize the distal ends of the tubes 194.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.